What is Due Diligence? Definition and Workplace PHS Impact

Due Diligence is the legal standard of care an employer must meet to prove they have taken every reasonable precaution (Reasonable Care) to protect the health and safety of their employees. In a Psychological Health and Safety (PHS) context, due diligence serves as an organization's primary defense against claims of negligence, regulatory violations, or costly legal liability.

The impact of a strong due diligence stance is the creation of a permanent, documented paper trail of protection. If a workplace psychological injury occurs, or if a human rights claim is filed, the organization must be legally equipped to demonstrate through objective evidence that it did not simply ignore the environmental risks. Instead, it must prove it followed a systematic, proactive process to actively prevent psychological harm.

How Due Diligence Relates to the PHS Standard (CSA Z1003 / ISO 45003)

Aligning Senior Commitment with the CSA Z1003 Framework

Under the CSA Z1003 and ISO 45003 standards, Due Diligence is operationalized through the Plan-Do-Check-Act (PDCA) cycle. This framework begins with a formal commitment to psychological health and safety signed by senior leadership. This commitment cannot just be a philosophy; it must be supported by a documented process for identifying workplace Psychosocial Factors that may lead to mental injury.

Applying the Hierarchy of Controls and Documenting Interventions

To maintain a defensible position, an employer must show clear evidence that the Hierarchy of Controls has been applied to mitigate identified workplace stressors. This means demonstrating that the organization actively attempted to alter toxic work designs through Elimination or managed them directly through clear Administrative Controls before expecting employees to simply absorb the stress.

Maintaining Training Records and the Duty to Inquire

Operational transparency is maintained through meticulous records of comprehensive training for both employees and managers, specifically covering hazard recognition. For leadership, this includes documented training on essential supervisory roles, such as the Duty to Inquire when an employee's behaviour or performance abruptly shifts. Finally, the entire system enters a cycle of continuous improvement driven by monitored outcomes, using regular audits and management reviews to verify that psychological health and safety measures remain both effective and consistently followed.

Why Due Diligence Matters for Leaders & HR

In the eyes of the law, "I didn't know" is never a valid defense. Due diligence is entirely about proving two distinct concepts: Foreseeability and action. If an organization is investigated by a health and safety regulator, a workers' compensation board, or a human rights tribunal, the burden of proof shifts. The employer must legally prove they exercised due diligence to prevent the specific injury.

A PHS-informed lens holds every level of management strictly accountable for maintaining the documentation that proves the organization is fulfilling its Duty of Care.

When a case is evaluated, the law asks one fundamental question:

Following the National Standard provides a clear, internationally recognized benchmark for what constitutes Reasonable Care. Without this structured framework, an organization is left highly vulnerable to claims of systemic workplace negligence.

How to Address Due Diligence in Your Organization

Psychological Health & Safety Due Diligence Audit

This assessment helps HR leaders and executives evaluate their current level of legal protection, documentation readiness, and foreseeability protocols under Canadian PHS guidelines.